The present invention relates in general to audio speaker systems for automotive vehicles, and, more specifically, to integration of flat speakers with automotive interior trim panels.
The use of traditional cone-shaped loudspeakers often compromises the design of vehicle interior trim panels by occupying space that could otherwise be utilized for interior storage or to add volume to the passenger cabin. Recent developments in flat panel speaker technology has provided the opportunity to place speakers on a given trim panel to increase available space for storage or other purposes.
A flat panel speaker may be used as a self-contained element which is separately manufactured and then assembled onto the vehicle interior. However, self-contained flat panel speakers may be difficult to integrate into a desired styling of the interior trim panels due to shape and/or mounting limitations. Thus, attempts have been made to integrate the exciter of a flat-panel speaker directly onto a trim panel element. Such integration may also result in reduced overall costs.
The prior art discloses attempts to incorporate the exciter of a flat panel speaker design onto a trim panel using the trim element itself as the vibrating diaphragm. However, significant difficulties have been encountered in this approach. For example, U.S. Pat. No. 7,050,593 illustrates use of an automotive headliner panel as the sound surface for a flat panel speaker. U.S. Pat. No. 6,377,695 similarly discloses an exciter attached to vehicle roof lining, door panels, dashboards, and rear parcel shelves, and it discloses foam materials for the radiating sound surface. Other materials typically used for the disclosed trim surfaces include glass-filled urethane foam and molded plastics such as PVC and PPO. Thus, the typical materials used for automotive trim surfaces tend to be sound absorbent and are far from ideal for use to propagate sound.
A further problem associated with existing deployments of flat panel speakers in interior trim panels relates to damping and isolation. By mounting an exciter directly to the backside of a headliner or other trim panel substrate, the sound production area (i.e., the region where panel vibrations generate sound) may extend to other assembled components on the panel (e.g., lighting components, panel attachment points, and electrical accessories) which may adversely affect the resonance of the acoustic surface and its ability to reproduce sound.
Yet another problem associated with known arrangements relates to inefficiency of the resulting speaker. The exciter must overcome its own mass when energized due to the fact that it is solely supported by its attachment with the panel surface. This limits voice coil excursion and the subsequent transmission of sound into the acoustic sound surface.